Just as with the match fixing allegations which continue to plague cricket, some confidential material has apparently been leaked. A third incident in recent times concerned the leaking of confidential emails from Darryl Hair after the ICC disowned him over the Pakistani forfeit test. All three incidents are unrelated, but one does wonder why no-one in cricket seems to be able to keep a secret. The implications for the management of cricket are severe: no commercial organisation can continue to function successfully if confidential information is leaked every time there might be some press interest in it. I wrote about this in a bit more detail in Court & Bowled.
As to who is telling the truth, it is not easy for outsiders to determine. As Nasser Hussain pointed out, team spirit is always high when a team is winning and tends to collapse when a team is losing. And once Mitchell Johnson returned as a bowler of the very highest class, no amount of team spirit was going to help the English tail play him (the main difference between the home and away Ashes in 2013/14 was that in England the English tail wagged often enough in a low scoring series to make a difference; in Australia Haddin scored crucial lower order runs in almost every innings whilst the English tail was destroyed by Johnson).
I would observe though that KP was a genuinely great player, and I don't doubt there were other villains in English cricket during his time, but he still has to ask himself why he fell out with so many of the teams for whom he played. And the management and former teammates have to ask themselves why they were not able to deal with a player who had played 100 tests despite his sins.